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1.
Life Sci Alliance ; 7(8)2024 Aug.
Article de Anglais | MEDLINE | ID: mdl-38843936

RÉSUMÉ

Lipid composition is conserved within sub-cellular compartments to maintain cell function. Lipidomic analyses of liver, muscle, white and brown adipose tissue (BAT) mitochondria revealed substantial differences in their glycerophospholipid (GPL) and free cholesterol (FC) contents. The GPL to FC ratio was 50-fold higher in brown than white adipose tissue mitochondria. Their purity was verified by comparison of proteomes with ER and mitochondria-associated membranes. A lipid signature containing PC and FC, calculated from the lipidomic profiles, allowed differentiation of mitochondria from BAT of mice housed at different temperatures. Elevating FC in BAT mitochondria prevented uncoupling protein (UCP) 1 function, whereas increasing GPL boosted it. Similarly, STARD3 overexpression facilitating mitochondrial FC import inhibited UCP1 function in primary brown adipocytes, whereas a knockdown promoted it. We conclude that the mitochondrial GPL/FC ratio is key for BAT function and propose that targeting it might be a promising strategy to promote UCP1 activity.


Sujet(s)
Tissu adipeux brun , Cholestérol , Lipidomique , Mitochondries , Protéine-1 de découplage , Animaux , Protéine-1 de découplage/métabolisme , Protéine-1 de découplage/génétique , Souris , Tissu adipeux brun/métabolisme , Cholestérol/métabolisme , Mitochondries/métabolisme , Lipidomique/méthodes , Spécificité d'organe , Souris de lignée C57BL , Tissu adipeux blanc/métabolisme , Glycérophospholipides/métabolisme , Mâle , Métabolisme lipidique
2.
Sci Rep ; 14(1): 13525, 2024 06 12.
Article de Anglais | MEDLINE | ID: mdl-38866945

RÉSUMÉ

The traditional nomenclature of enteroendocrine cells (EECs), established in 1977, applied the "one cell - one hormone" dogma, which distinguishes subpopulations based on the secretion of a specific hormone. These hormone-specific subpopulations included S cells for secretin (SCT), K cells for glucose-dependent insulinotropic polypeptide (GIP), N cells producing neurotensin (NTS), I cells producing cholecystokinin (CCK), D cells producing somatostatin (SST), and others. In the past 15 years, reinvestigations into murine and human organoid-derived EECs, however, strongly questioned this dogma and established that certain EECs coexpress multiple hormones. Using the Gut Cell Atlas, the largest available single-cell transcriptome dataset of human intestinal cells, this study consolidates that the original dogma is outdated not only for murine and human organoid-derived EECs, but also for primary human EECs, showing that the expression of certain hormones is not restricted to their designated cell type. Moreover, specific analyses into SCT-expressing cells reject the presence of any cell population that exhibits significantly elevated secretin expression compared to other cell populations, previously referred to as S cells. Instead, this investigation indicates that secretin production is realized jointly by other enteroendocrine subpopulations, validating corresponding observations in murine EECs also for human EECs. Furthermore, our findings corroborate that SCT expression peaks in mature EECs, in contrast, progenitor EECs exhibit markedly lower expression levels, supporting the hypothesis that SCT expression is a hallmark of EEC maturation.


Sujet(s)
Cellules entéroendocrines , Analyse de profil d'expression de gènes , Sécrétine , Analyse sur cellule unique , Humains , Cellules entéroendocrines/métabolisme , Sécrétine/métabolisme , Sécrétine/génétique , Analyse sur cellule unique/méthodes , Souris , Animaux , Transcriptome , Différenciation cellulaire , Organoïdes/métabolisme , Organoïdes/cytologie , Cholécystokinine/métabolisme , Cholécystokinine/génétique , Somatostatine/métabolisme , Somatostatine/génétique , Analyse de l'expression du gène de la cellule unique
3.
Sci Data ; 11(1): 524, 2024 May 22.
Article de Anglais | MEDLINE | ID: mdl-38778016

RÉSUMÉ

Datasets consist of measurement data and metadata. Metadata provides context, essential for understanding and (re-)using data. Various metadata standards exist for different methods, systems and contexts. However, relevant information resides at differing stages across the data-lifecycle. Often, this information is defined and standardized only at publication stage, which can lead to data loss and workload increase. In this study, we developed Metadatasheet, a metadata standard based on interviews with members of two biomedical consortia and systematic screening of data repositories. It aligns with the data-lifecycle allowing synchronous metadata recording within Microsoft Excel, a widespread data recording software. Additionally, we provide an implementation, the Metadata Workbook, that offers user-friendly features like automation, dynamic adaption, metadata integrity checks, and export options for various metadata standards. By design and due to its extensive documentation, the proposed metadata standard simplifies recording and structuring of metadata for biomedical scientists, promoting practicality and convenience in data management. This framework can accelerate scientific progress by enhancing collaboration and knowledge transfer throughout the intermediate steps of data creation.


Sujet(s)
Gestion des données , Métadonnées , Recherche biomédicale , Gestion des données/normes , Métadonnées/normes , Logiciel
4.
Neurogastroenterol Motil ; : e14761, 2024 Feb 11.
Article de Anglais | MEDLINE | ID: mdl-38342975

RÉSUMÉ

INTRODUCTION: The herbal preparation STW 5 ameliorates functional dyspepsia partly by relaxing smooth muscle of the proximal stomach, thus improving gastric accommodation. We explored the unknown pathways responsible for this effect by testing targets known to modulate gastric smooth muscle relaxation. METHODS: STW 5-induced relaxation of smooth muscle strips from guinea pig gastric corpus before and after pharmacological interventions were recorded with force transducers in an organ bath. ORAI1 mRNA expression was tested in the proximal stomach. KEY RESULTS: Blockade of Ca2+ -activated K+ and Cl- channels, voltage-gated L- or T-type Ca2+ channels, TRPA1-, TRPV1-, adenosine or 5-HT4 receptors, antagonizing ryanodine receptors, inhibiting cyclooxygenase or sarcoplasmic reticulum calcium ATPase did not affect STW 5-evoked relaxation. Likewise, protein-kinase A or G were not involved. However, the relaxation evoked by STW 5 was significantly reduced by phorbol-12-myristat-13-acetat, an activator of protein-kinase C, by 2- aminoethyldiphenylborinate, an inhibitor of the IP3 receptor-mediated Ca2+ release from the sarcoplasmic reticulum or by SKF-96365, a nonselective store-operated calcium entry (SOCE) blocker. Furthermore, the mixed TRPC3/SOCE inhibitor Pyr3, but not the selective TRPC3 blocker Pyr10, reduced the effect of STW 5. Finally, BTP2, a potent blocker of ORAI-coupled SOCE, almost abolished STW 5-evoked relaxation. Expression of ORAI1 could be demonstrated in the corpus/fundus. CONCLUSIONS & INFERENCES: STW 5 inhibited SOCE, most likely ORAI channels, which are modulated by IP3- and PKC-dependent mechanisms. Our findings impact on the design of drugs to induce muscle relaxation and help identify phytochemicals with similar modes of actions to treat gastrointestinal disturbances.

5.
Cell Rep ; 42(9): 113131, 2023 Sep 26.
Article de Anglais | MEDLINE | ID: mdl-37708023

RÉSUMÉ

Cold-induced brown adipose tissue (BAT) activation is considered to improve metabolic health. In murine BAT, cold increases the fundamental molecule for mitochondrial function, nicotinamide adenine dinucleotide (NAD+), but limited knowledge of NAD+ metabolism during cold in human BAT metabolism exists. We show that cold increases the serum metabolites of the NAD+ salvage pathway (nicotinamide and 1-methylnicotinamide) in humans. Additionally, individuals with cold-stimulated BAT activation have decreased levels of metabolites from the de novo NAD+ biosynthesis pathway (tryptophan, kynurenine). Serum nicotinamide correlates positively with cold-stimulated BAT activation, whereas tryptophan and kynurenine correlate negatively. Furthermore, the expression of genes involved in NAD+ biosynthesis in BAT is related to markers of metabolic health. Our data indicate that cold increases serum tryptophan conversion to nicotinamide to be further utilized by BAT. We conclude that NAD+ metabolism is activated upon cold in humans and is probably regulated in a coordinated fashion by several tissues.

6.
Mol Cell Proteomics ; 22(9): 100632, 2023 09.
Article de Anglais | MEDLINE | ID: mdl-37586548

RÉSUMÉ

Myeloid-derived suppressor cells (MDSC) are a heterogeneous cell population of incompletely differentiated immune cells. They are known to suppress T cell activity and are implicated in multiple chronic diseases, which make them an attractive cell population for drug discovery. Here, we characterized the baseline proteomes and phospho-proteomes of mouse MDSC differentiated from a progenitor cell line to a depth of 7000 proteins and phosphorylation sites. We also validated the cellular system for drug discovery by recapitulating and identifying known and novel molecular responses to the well-studied MDSC drugs entinostat and mocetinostat. We established a high-throughput drug screening platform using a MDSC/T cell coculture system and assessed the effects of ∼21,000 small molecule compounds on T cell proliferation and IFN-γ secretion to identify novel MDSC modulator. The most promising candidates were validated in a human MDSC system, and subsequent proteomic experiments showed significant upregulation of several proteins associated with the reduction of reactive oxygen species (ROS). Proteome-wide solvent-induced protein stability assays identified Acyp1 and Cd74 as potential targets, and the ROS-reducing drug phenotype was validated by measuring ROS levels in cells in response to compound, suggesting a potential mode of action. We anticipate that the data and chemical tools developed in this study will be valuable for further research on MDSC and related drug discovery.


Sujet(s)
Cellules myéloïdes suppressives , Souris , Humains , Animaux , Cellules myéloïdes suppressives/métabolisme , Tests de criblage à haut débit , Protéome/métabolisme , Protéomique , Espèces réactives de l'oxygène/métabolisme
7.
Elife ; 122023 08 21.
Article de Anglais | MEDLINE | ID: mdl-37603466

RÉSUMÉ

Delta-like homolog 1 (Dlk1), an inhibitor of adipogenesis, controls the cell fate of adipocyte progenitors. Experimental data presented here identify two independent regulatory mechanisms, transcriptional and translational, by which Ifrd1 (TIS7) and its orthologue Ifrd2 (SKMc15) regulate Dlk1 levels. Mice deficient in both Ifrd1 and Ifrd2 (dKO) had severely reduced adipose tissue and were resistant to high-fat diet-induced obesity. Wnt signaling, a negative regulator of adipocyte differentiation, was significantly upregulated in dKO mice. Elevated levels of the Wnt/ß-catenin target protein Dlk1 inhibited the expression of adipogenesis regulators Pparg and Cebpa, and fatty acid transporter Cd36. Although both Ifrd1 and Ifrd2 contributed to this phenotype, they utilized two different mechanisms. Ifrd1 acted by controlling Wnt signaling and thereby transcriptional regulation of Dlk1. On the other hand, distinctive experimental evidence showed that Ifrd2 acts as a general translational inhibitor significantly affecting Dlk1 protein levels. Novel mechanisms of Dlk1 regulation in adipocyte differentiation involving Ifrd1 and Ifrd2 are based on experimental data presented here.


Sujet(s)
Adipogenèse , Protéines de liaison au calcium , Protéines précoces immédiates , Protéines membranaires , Animaux , Souris , Adipocytes , Adipogenèse/génétique , Tissu adipeux , Protéines de liaison au calcium/génétique , Antigènes CD36 , Différenciation cellulaire , Protéines membranaires/génétique
8.
Nat Commun ; 14(1): 3548, 2023 06 15.
Article de Anglais | MEDLINE | ID: mdl-37322067

RÉSUMÉ

Lipoic acid is an essential enzyme cofactor in central metabolic pathways. Due to its claimed antioxidant properties, racemic (R/S)-lipoic acid is used as a food supplement but is also investigated as a pharmaceutical in over 180 clinical trials covering a broad range of diseases. Moreover, (R/S)-lipoic acid is an approved drug for the treatment of diabetic neuropathy. However, its mechanism of action remains elusive. Here, we performed chemoproteomics-aided target deconvolution of lipoic acid and its active close analog lipoamide. We find that histone deacetylases HDAC1, HDAC2, HDAC3, HDAC6, HDAC8, and HDAC10 are molecular targets of the reduced form of lipoic acid and lipoamide. Importantly, only the naturally occurring (R)-enantiomer inhibits HDACs at physiologically relevant concentrations and leads to hyperacetylation of HDAC substrates. The inhibition of HDACs by (R)-lipoic acid and lipoamide explain why both compounds prevent stress granule formation in cells and may also provide a molecular rationale for many other phenotypic effects elicited by lipoic acid.


Sujet(s)
Inhibiteurs de désacétylase d'histone , Acide lipoïque , Inhibiteurs de désacétylase d'histone/pharmacologie , Inhibiteurs de désacétylase d'histone/composition chimique , Acide lipoïque/pharmacologie , Histone deacetylases/métabolisme , Antioxydants/pharmacologie
9.
Metabolites ; 13(3)2023 Mar 05.
Article de Anglais | MEDLINE | ID: mdl-36984827

RÉSUMÉ

Human brain metabolism is susceptible to temperature changes. It has been suggested that the supraclavicular brown adipose tissue (BAT) protects the brain from these fluctuations by regulating heat production through the presence of uncoupling protein 1 (UCP-1). It remains unsolved whether inter-individual variation in the expression of UCP-1, which represents the thermogenic capacity of the supraclavicular BAT, is linked with brain metabolism during cold stress. Ten healthy human participants underwent 18F-FDG PET scanning of the brain under cold stimulus to determine brain glucose uptake (BGU). On a separate day, an excision biopsy of the supraclavicular fat-the fat proximal to the carotid arteries supplying the brain with warm blood-was performed to determine the mRNA expression of the thermogenic protein UCP-1. Expression of UCP-1 in supraclavicular BAT was directly related to the whole brain glucose uptake rate determined under cold stimulation (rho = 0.71, p = 0.03). In sub-compartmental brain analysis, UCP-1 expression in supraclavicular BAT was directly related to cold-stimulated glucose uptake rates in the hypothalamus, medulla, midbrain, limbic system, frontal lobe, occipital lobe, and parietal lobe (all rho ≥ 0.67, p < 0.05). These relationships were independent of body mass index and age. When analysing gene expressions of BAT secretome, we found a positive correlation between cold-stimulated BGU and DIO2. These findings provide evidence of functional links between brain metabolism under cold stimulation and UCP-1 and DIO2 expressions in BAT in humans. More research is needed to evaluate the importance of these findings in clinical outcomes, for instance, in examining the supporting role of BAT in cognitive functions under cold stress.

10.
Nat Immunol ; 24(3): 501-515, 2023 03.
Article de Anglais | MEDLINE | ID: mdl-36797499

RÉSUMÉ

Blocking pyrimidine de novo synthesis by inhibiting dihydroorotate dehydrogenase is used to treat autoimmunity and prevent expansion of rapidly dividing cell populations including activated T cells. Here we show memory T cell precursors are resistant to pyrimidine starvation. Although the treatment effectively blocked effector T cells, the number, function and transcriptional profile of memory T cells and their precursors were unaffected. This effect occurred in a narrow time window in the early T cell expansion phase when developing effector, but not memory precursor, T cells are vulnerable to pyrimidine starvation. This vulnerability stems from a higher proliferative rate of early effector T cells as well as lower pyrimidine synthesis capacity when compared with memory precursors. This differential sensitivity is a drug-targetable checkpoint that efficiently diminishes effector T cells without affecting the memory compartment. This cell fate checkpoint might therefore lead to new methods to safely manipulate effector T cell responses.


Sujet(s)
Pyrimidines , Cycle cellulaire , Différenciation cellulaire
11.
Eur J Nucl Med Mol Imaging ; 50(6): 1597-1606, 2023 05.
Article de Anglais | MEDLINE | ID: mdl-36764966

RÉSUMÉ

PURPOSE: Secretin activates brown adipose tissue (BAT) and induces satiation in both mice and humans. However, the exact brain mechanism of this satiety inducing, secretin-mediated gut-BAT-brain axis is largely unknown. METHODS AND RESULTS: In this placebo-controlled, single-blinded neuroimaging study, firstly using [18F]-fluorodeoxyglucose (FDG) PET measures (n = 15), we established that secretin modulated brain glucose consumption through the BAT-brain axis. Predominantly, we found that BAT and caudate glucose uptake levels were negatively correlated (r = -0.54, p = 0.037) during secretin but not placebo condition. Then, using functional magnetic resonance imaging (fMRI; n = 14), we found that secretin improved inhibitory control and downregulated the brain response to appetizing food images. Finally, in a PET-fMRI fusion analysis (n = 10), we disclosed the patterned correspondence between caudate glucose uptake and neuroactivity to reward and inhibition, showing that the secretin-induced neurometabolic coupling patterns promoted satiation. CONCLUSION: These findings suggest that secretin may modulate the BAT-brain metabolic crosstalk and subsequently the neurometabolic coupling to induce satiation. The study advances our understanding of the secretin signaling in motivated eating behavior and highlights the potential role of secretin in treating eating disorders and obesity. TRIAL REGISTRATION: EudraCT no. 2016-002373-35, registered 2 June 2016; Clinical Trials no. NCT03290846, registered 25 September 2017.


Sujet(s)
Tissu adipeux brun , Appétit , Axe cerveau-intestin , Encéphale , Comportement alimentaire , Neuroimagerie fonctionnelle , Sensation de satiété , Sécrétine , Tissu adipeux brun/effets des médicaments et des substances chimiques , Tissu adipeux brun/métabolisme , Tissu adipeux brun/physiologie , Appétit/effets des médicaments et des substances chimiques , Appétit/physiologie , Encéphale/effets des médicaments et des substances chimiques , Encéphale/métabolisme , Encéphale/physiologie , Sécrétine/métabolisme , Sécrétine/pharmacologie , Sensation de satiété/effets des médicaments et des substances chimiques , Sensation de satiété/physiologie , Axe cerveau-intestin/effets des médicaments et des substances chimiques , Axe cerveau-intestin/physiologie , Méthode en simple aveugle , Imagerie par résonance magnétique , Tomographie par émission de positons , Glucose/métabolisme , Récompense , Transduction du signal/effets des médicaments et des substances chimiques , Humains , Comportement alimentaire/effets des médicaments et des substances chimiques , Aliments
12.
Cells ; 12(3)2023 01 30.
Article de Anglais | MEDLINE | ID: mdl-36766790

RÉSUMÉ

Obesity is a complex disease highly related to diet and lifestyle and is associated with low amount of thermogenic adipocytes. Therapeutics that regulate brown adipocyte recruitment and activity represent interesting strategies to fight overweight and associated comorbidities. Recent studies suggest a role for several fatty acids and their metabolites, called lipokines, in the control of thermogenesis. The purpose of this work was to analyze the role of several lipokines in the control of brown/brite adipocyte formation. We used a validated human adipocyte model, human multipotent adipose-derived stem cell model (hMADS). In the absence of rosiglitazone, hMADS cells differentiate into white adipocytes, but convert into brite adipocytes upon rosiglitazone or prostacyclin 2 (PGI2) treatment. Gene expression was quantified using RT-qPCR and protein levels were assessed by Western blotting. We show here that lipokines such as 12,13-diHOME, 12-HEPE, 15dPGJ2 and 15dPGJ3 were not able to induce browning of white hMADS adipocytes. However, both fatty acid esters of hydroxy fatty acids (FAHFAs), 9-PAHPA and 9-PAHSA potentiated brown key marker UCP1 mRNA levels. Interestingly, CTA2, the stable analog of thromboxane A2 (TXA2), but not its inactive metabolite TXB2, inhibited the rosiglitazone and PGI2-induced browning of hMADS adipocytes. These results pinpoint TXA2 as a lipokine inhibiting brown adipocyte formation that is antagonized by PGI2. Our data open new horizons in the development of potential therapies based on the control of thromboxane A2/prostacyclin balance to combat obesity and associated metabolic disorders.


Sujet(s)
Acides gras , Thromboxane A2 , Humains , Thromboxane A2/métabolisme , Rosiglitazone/pharmacologie , Acides gras/métabolisme , Adipocytes bruns/métabolisme , Obésité/métabolisme , Prostaglandines I/métabolisme
13.
Nat Commun ; 13(1): 6830, 2022 11 11.
Article de Anglais | MEDLINE | ID: mdl-36369285

RÉSUMÉ

Current concepts regarding the biology of aging are primarily based on studies aimed at identifying factors regulating lifespan. However, lifespan as a sole proxy measure for aging can be of limited value because it may be restricted by specific pathologies. Here, we employ large-scale phenotyping to analyze hundreds of markers in aging male C57BL/6J mice. For each phenotype, we establish lifetime profiles to determine when age-dependent change is first detectable relative to the young adult baseline. We examine key lifespan regulators (putative anti-aging interventions; PAAIs) for a possible countering of aging. Importantly, unlike most previous studies, we include in our study design young treated groups of animals, subjected to PAAIs prior to the onset of detectable age-dependent phenotypic change. Many PAAI effects influence phenotypes long before the onset of detectable age-dependent change, but, importantly, do not alter the rate of phenotypic change. Hence, these PAAIs have limited effects on aging.


Sujet(s)
Vieillissement , Longévité , Souris , Animaux , Mâle , Longévité/génétique , Souris de lignée C57BL , Vieillissement/physiologie , Phénotype
14.
Mol Metab ; 61: 101499, 2022 07.
Article de Anglais | MEDLINE | ID: mdl-35470094

RÉSUMÉ

OBJECTIVE: Classical ATP-independent non-shivering thermogenesis enabled by uncoupling protein 1 (UCP1) in brown adipose tissue (BAT) is activated, but not essential for survival, in the cold. It has long been suspected that futile ATP-consuming substrate cycles also contribute to thermogenesis and can partially compensate for the genetic ablation of UCP1 in mouse models. Futile ATP-dependent thermogenesis could thereby enable survival in the cold even when brown fat is less abundant or missing. METHODS: In this study, we explore different potential sources of UCP1-independent thermogenesis and identify a futile ATP-consuming triglyceride/fatty acid cycle as the main contributor to cellular heat production in brown adipocytes lacking UCP1. We uncover the mechanism on a molecular level and pinpoint the key enzymes involved using pharmacological and genetic interference. RESULTS: ATGL is the most important lipase in terms of releasing fatty acids from lipid droplets, while DGAT1 accounts for the majority of fatty acid re-esterification in UCP1-ablated brown adipocytes. Furthermore, we demonstrate that chronic cold exposure causes a pronounced remodeling of adipose tissues and leads to the recruitment of lipid cycling capacity specifically in BAT of UCP1-knockout mice, possibly fueled by fatty acids from white fat. Quantification of triglyceride/fatty acid cycling clearly shows that UCP1-ablated animals significantly increase turnover rates at room temperature and below. CONCLUSION: Our results suggest an important role for futile lipid cycling in adaptive thermogenesis and total energy expenditure.


Sujet(s)
Tissu adipeux brun , Thermogenèse , Adénosine triphosphate/métabolisme , Tissu adipeux brun/métabolisme , Animaux , Acides gras/métabolisme , Souris , Souris knockout , Triglycéride/métabolisme , Protéine-1 de découplage/génétique , Protéine-1 de découplage/métabolisme
15.
EMBO Mol Med ; 14(5): e14742, 2022 05 09.
Article de Anglais | MEDLINE | ID: mdl-35437952

RÉSUMÉ

The regular overconsumption of energy-dense foods (rich in lipids and sugars) results in elevated intestinal nutrient absorption and consequently excessive accumulation of lipids in the liver, adipose tissue, skeletal muscles, and other organs. This can eventually lead to obesity and obesity-associated diseases such as type 2 diabetes (T2D), non-alcoholic fatty liver disease (NAFLD), cardiovascular disease, and certain types of cancer, as well as aggravate inflammatory bowel disease (IBD). Therefore, targeting the pathways that regulate intestinal nutrient absorption holds significant therapeutic potential. In this review, we discuss the molecular and cellular mechanisms controlling intestinal lipid handling, their relevance to the development of metabolic diseases, and emerging therapeutic strategies.


Sujet(s)
Diabète de type 2 , Stéatose hépatique non alcoolique , Tissu adipeux/métabolisme , Diabète de type 2/métabolisme , Humains , Lipides/usage thérapeutique , Foie/métabolisme , Obésité/métabolisme
16.
Commun Biol ; 5(1): 280, 2022 03 29.
Article de Anglais | MEDLINE | ID: mdl-35351968

RÉSUMÉ

Pharmacological activation of brown adipose tissue (BAT) is an attractive approach for increasing energy expenditure to counteract obesity. Given the side-effects of known activators of BAT, we studied inhibitors of BAT as a novel, alternative concept to regulate energy expenditure. We focused on G-protein-coupled receptors that are one of the major targets of clinically used drugs. Here, we identify GPR183, also known as EBI2, as the most highly expressed inhibitory G-protein-coupled receptor in BAT among the receptors examined. Activation of EBI2 using its endogenous ligand 7α,25-dihydroxycholesterol significantly decreases BAT-mediated energy expenditure in mice. In contrast, mice deficient for EBI2 show increased energy dissipation in response to cold. Interestingly, only thermogenic adipose tissue depots - BAT and subcutaneous white adipose tissue -respond to 7α,25-dihydroxycholesterol treatment/EBI2 activation but not gonadal white fat, which has the lowest thermogenic capacity. EBI2 activation in brown adipocytes significantly reduces norepinephrine-induced cAMP production, whereas pharmacological inhibition or genetic ablation of EBI2 results in an increased response. Importantly, EBI2 significantly inhibits norepinephrine-induced activation of human brown adipocytes. Our data identify the 7α,25-dihydroxycholesterol/EBI2 signaling pathway as a so far unknown BAT inhibitor. Understanding the inhibitory regulation of BAT might lead to novel pharmacological approaches to increase the activity of thermogenic adipose tissue and whole body energy expenditure in humans.


Sujet(s)
Adipocytes bruns , Tissu adipeux brun , Métabolisme énergétique , Récepteurs couplés aux protéines G , Adipocytes bruns/métabolisme , Tissu adipeux brun/métabolisme , Animaux , Humains , Souris , Norépinéphrine/métabolisme , Récepteurs couplés aux protéines G/génétique , Récepteurs couplés aux protéines G/métabolisme , Thermogenèse
17.
Am J Physiol Endocrinol Metab ; 322(1): E54-E62, 2022 01 01.
Article de Anglais | MEDLINE | ID: mdl-34806426

RÉSUMÉ

The cardiac benefits of gastrointestinal hormones have been of interest in recent years. The aim of this study was to explore the myocardial and renal effects of the gastrointestinal hormone secretin in the GUTBAT trial (NCT03290846). A placebo-controlled crossover study was conducted on 15 healthy males in fasting conditions, where subjects were blinded to the intervention. Myocardial glucose uptake was measured with [18F]2-fluoro-2-deoxy-d-glucose ([18F]FDG) positron emission tomography. Kidney function was measured with [18F]FDG renal clearance and estimated glomerular filtration rate (eGFR). Secretin increased myocardial glucose uptake compared with placebo (secretin vs. placebo, means ± SD, 15.5 ± 7.4 vs. 9.7 ± 4.9 µmol/100 g/min, 95% confidence interval (CI) [2.2, 9.4], P = 0.004). Secretin also increased [18F]FDG renal clearance (44.5 ± 5.4 vs. 39.5 ± 8.5 mL/min, 95%CI [1.9, 8.1], P = 0.004), and eGFR was significantly increased from baseline after secretin, compared with placebo (17.8 ± 9.8 vs. 6.0 ± 5.2 ΔmL/min/1.73 m2, 95%CI [6.0, 17.6], P = 0.001). Our results implicate that secretin increases heart work and renal filtration, making it an interesting drug candidate for future studies in heart and kidney failure.NEW & NOTEWORTHY Secretin increases myocardial glucose uptake compared with placebo, supporting a previously proposed inotropic effect. Secretin also increased renal filtration rate.


Sujet(s)
Coeur/effets des médicaments et des substances chimiques , Rein/effets des médicaments et des substances chimiques , Rein/métabolisme , Myocarde/métabolisme , Sécrétine/administration et posologie , Adolescent , Adulte , Sujet âgé , Études croisées , Jeûne , Fluorodésoxyglucose F18/métabolisme , Débit de filtration glomérulaire , Glucose/métabolisme , Volontaires sains , Humains , Perfusions veineuses , Mâle , Adulte d'âge moyen , Tomographie par émission de positons/méthodes , Radiopharmaceutiques/métabolisme , Jeune adulte
18.
Am J Physiol Endocrinol Metab ; 322(2): E85-E100, 2022 02 01.
Article de Anglais | MEDLINE | ID: mdl-34927460

RÉSUMÉ

Activation of uncoupling protein 1 (UCP1) in brown adipose tissue (BAT) upon cold stimulation leads to substantial increase in energy expenditure to defend body temperature. Increases in energy expenditure after a high-caloric food intake, termed diet-induced thermogenesis, are also attributed to BAT. These properties render BAT a potential target to combat diet-induced obesity. However, studies investigating the role of UCP1 to protect against diet-induced obesity are controversial and rely on the phenotyping of a single constitutive UCP1-knockout model. To address this issue, we generated a novel UCP1-knockout model by Cre-mediated deletion of exon 2 in the UCP1 gene. We studied the effect of constitutive UCP1 knockout on metabolism and the development of diet-induced obesity. UCP1 knockout and wild-type mice were housed at 30°C and fed a control diet for 4 wk followed by 8 wk of high-fat diet. Body weight and food intake were monitored continuously over the course of the study, and indirect calorimetry was used to determine energy expenditure during both feeding periods. Based on Western blot analysis, thermal imaging and noradrenaline test, we confirmed the lack of functional UCP1 in knockout mice. However, body weight gain, food intake, and energy expenditure were not affected by loss of UCP1 function during both feeding periods. We introduce a novel UCP1-KO mouse enabling the generation of conditional UCP1-knockout mice to scrutinize the contribution of UCP1 to energy metabolism in different cell types or life stages. Our results demonstrate that UCP1 does not protect against diet-induced obesity at thermoneutrality.NEW & NOTEWORTHY We provide evidence that the abundance of UCP1 does not influence energy metabolism at thermoneutrality studying a novel Cre-mediated UCP1-KO mouse model. This model will be a foundation for a better understanding of the contribution of UCP1 in different cell types or life stages to energy metabolism.


Sujet(s)
Alimentation riche en graisse/effets indésirables , Obésité/étiologie , Obésité/métabolisme , Température , Protéine-1 de découplage/métabolisme , Tissu adipeux brun/métabolisme , Animaux , Calorimétrie indirecte/méthodes , Prédisposition aux maladies/métabolisme , Consommation alimentaire/génétique , Métabolisme énergétique/génétique , Femelle , Mâle , Souris , Souris de lignée C57BL , Souris knockout , Obésité/génétique , Thermogenèse/génétique , Protéine-1 de découplage/génétique , Prise de poids/génétique
19.
Life Sci Alliance ; 5(3)2022 03.
Article de Anglais | MEDLINE | ID: mdl-34857647

RÉSUMÉ

In Wilson disease, excessive copper accumulates in patients' livers and may, upon serum leakage, severely affect the brain according to current viewpoints. Present remedies aim at avoiding copper toxicity by chelation, for example, by D-penicillamine (DPA) or bis-choline tetrathiomolybdate (ALXN1840), the latter with a very high copper affinity. Hence, ALXN1840 may potentially avoid neurological deterioration that frequently occurs upon DPA treatment. As the etiology of such worsening is unclear, we reasoned that copper loosely bound to albumin, that is, mimicking a potential liver copper leakage into blood, may damage cells that constitute the blood-brain barrier, which was found to be the case in an in vitro model using primary porcine brain capillary endothelial cells. Such blood-brain barrier damage was avoided by ALXN1840, plausibly due to firm protein embedding of the chelator bound copper, but not by DPA. Mitochondrial protection was observed, a prerequisite for blood-brain barrier integrity. Thus, high-affinity copper chelators may minimize such deterioration in the treatment of neurologic Wilson disease.


Sujet(s)
Barrière hémato-encéphalique/métabolisme , Barrière hémato-encéphalique/anatomopathologie , Cuivre/métabolisme , Molybdène/pharmacologie , Pénicillamine/pharmacologie , Animaux , Transport biologique , Marqueurs biologiques , Barrière hémato-encéphalique/imagerie diagnostique , Encéphale/imagerie diagnostique , Encéphale/effets des médicaments et des substances chimiques , Encéphale/métabolisme , Encéphale/anatomopathologie , Survie cellulaire , Chélateurs/pharmacologie , Cuivre/effets indésirables , Cuivre/composition chimique , Cellules endothéliales/effets des médicaments et des substances chimiques , Cellules endothéliales/métabolisme , Humains , Souris transgéniques , Mitochondries/métabolisme , Mitochondries/ultrastructure , Modèles moléculaires , Tomographie par émission de positons , Liaison aux protéines , Rats , Sérumalbumine/composition chimique , Sérumalbumine/métabolisme , Relation structure-activité
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